The deal continues a long-standing agreement between the pair to provide rental services across a portfolio of European consumer sites.
Car hire through Hertz will be available through what Opodo is calling a one-stop-shop on its sites in the UK, Italy, France and Germany.
Opodo chief executive Ignacio Martos said: “The relationship that we have with Hertz allows Opodo to continue to offer its customers the very best in terms of convenience, quality and reliability.
“As a market leader in its field, Hertz offers innovative car rental and wide consumer choice, making this partnership a perfect fit for us.”
The pair will also continue to work through the OpenTravel Alliance scheme to create e-commerce standards across a range of major online travel providers.
Hertz European director for travel distribution, Gina Costa, said: “We are constantly looking for ways of improving our service offering.
“With Opodo, our customers have access to more choice and additional benefits via a simple and effective online booking process.”